Low-power radio-frequency receiver

ABSTRACT

A low-power RF receiver has a decreased current consumption. The receiver may be used in control devices, such as battery-powered motorized window treatments and two-wire dimmer switches. The receiver uses an RF sub-sampling technique to check for RF signals and then puts the receiver to sleep for a sleep time that is longer than a packet length of a transmitted packet to conserve battery power. The receiver compares detected RF energy to a threshold that may be increased to decrease the sensitivity of the receiver and increase the battery lifetime. After detecting an RF signal, the receiver is put to sleep for a snooze time that is longer than the sleep time and just slightly shorter than the time between two consecutive transmitted packets.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a non-provisional application of commonly-assignedU.S. Provisional Application No. 61/451,960, filed Mar. 11, 2011; U.S.Provisional Application No. 61/530,799, filed Sep. 2, 2011; and U.S.Provisional Application No. 61/547,319, filed Oct. 14, 2011, allentitled MOTORIZED WINDOW TREATMENT, the entire disclosures of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radio-frequency (RF) load controlsystem, and more specifically, to a low-power RF receiver for use in RFcontrol devices, such as, a battery-powered motorized window treatmentor a two-wire dimmer switch.

2. Description of the Related Art

Control systems for controlling electrical loads, such as lights,motorized window treatments, and fans, are known. Such control systemsoften use the transmission of radio-frequency (RF) signals to providewireless communication between the control devices of the system. Theprior art lighting control systems include wireless remote controls,such as, table-top and wall-mounted master controls (e.g., keypads) andcar visor controls. The master controls of the prior art lightingcontrol system each include a plurality of buttons and transmit RFsignals to load control devices (such as dimmer switches) to control theintensities of controlled lighting loads. The master controls may alsoeach include one or more visual indicators, e.g., light-emitting diodes(LEDs), for providing feedback to users of the lighting control system.The car visor controls are able to be clipped to the visor of anautomobile and include one or more buttons for controlling the lightingloads of the lighting control system. An example of a prior art RFlighting control system is disclosed in commonly-assigned U.S. Pat. No.5,905,442, issued on May 18, 1999, entitled METHOD AND APPARATUS FORCONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTELOCATIONS, the entire disclosure of which is hereby incorporated byreference.

Some of the wireless control devices of the prior art lighting controlsystems are powered by batteries, which have limited lifetimes that aredependent upon the current drawn from the batteries as well as how oftenthe control devices are used. The RF circuitry (i.e., the transmitters,receivers, or transceivers) of the wireless control devices is one ofthe primary consumers of battery power in the devices. Therefore,typical prior art battery-powered wireless control devices haveattempted to limit the amount of time that the control devices areactively transmitting RF signals. In addition, when the prior artbattery-powered wireless control devices are not presently transmittingor receiving RF signals, the RF circuitry is put into a sleep mode inwhich these circuits drawn less current from the batteries. The RFcircuitry is periodically woken up to determine if any RF signals arebeing received. Thus, the amount of time that the RF circuits are awakeas compared to the amount of time that the RF circuits are asleepaffects the amount of current drawn from the batteries as well as thelifetime of the batteries.

U.S. Pat. No. 7,869,481, issued Dec. 28, 2010, entitled LOW POWER RFCONTROL SYSTEM, describes a motorized window treatment having an RFreceiver, for allowing the motorized window treatment to be controlledfrom a handheld RF remote control. The remote control transmits commandsignals that each include a pre-sync pulse time and subsequent messagedata. To determine if an RF command signal is being transmitted by theRF remote control, the RF receiver of the motorized window treatmentperiodically wakes up for a short period of time at a rate that ensuresthat the RF receiver checks for RF signals at least two times during theamount of time required to transmit the pre-sync pulse time of eachcontrol signal. For example, if the pre-sync pulse time is 30milliseconds, the RF receiver wakes up at least two times each 30milliseconds. Thus, the amount of time that the RF circuitry is awake ascompared to being in the sleep mode is dependent upon a characteristicof the command signals, i.e., the length of the pre-sync pulse time, andmust be shorter than the pre-sync pulse time. Therefore, the sleep timecannot be increased (to thus decrease the power consumption of the RFreceiver) without increasing the pre-sync pulse time, which willdecrease the throughput of the system. In addition, the length of thecommand signals may be limited by national or regional standards.

Therefore, there is a need for a low-power RF receiver that may be usedin battery-powered control devices to lead to longer battery lifetimes.Particularly, there is a need for a low-power RF receiver that is ableto check for RF signals at a rate that is not limited by acharacteristic of each of the transmitted RF signals.

SUMMARY OF THE INVENTION

The present invention provides a low-power radio-frequency (RF) receiverthat is characterized by a decreased current consumption over prior artRF receivers. The low-power RF receiver may be used in, for example, abattery-powered control device, such as a motorized window treatmentthat controls the position of a covering material that is adapted tohang in front of an opening, such as a window. As a result of using thelow-power RF receiver, the battery-powered motorized window treatmenthas a much longer (and more practical) lifetime than typical prior artbattery-powered motorized window treatments (e.g., approximately threeyears). The low-power RF receiver is operable to receive RF signals fromvarious types of RF transmitters, such as, for example, battery-poweredremote controls, occupancy sensors, vacancy sensors, daylight sensors,temperature sensors, humidity sensors, security sensors, proximitysensors, keypads, key fobs, cell phones, smart phones, tablets, personaldigital assistants, personal computers, timeclocks, audio-visualcontrols, safety devices, central control transmitters, or anycombination of these input devices.

The low-power RF receiver is used in a load control system having an RFtransmitter that transmits a number of sequential packets via RF signalswith each packets including the same command and having a packet length.The low-power RF receiver is operable to use an RF sub-samplingtechnique to check for the RF signals and then put the RF receiver tosleep for a sleep time that is longer than the packet length of thepackets to thus conserve battery power and lengthen the lifetime of thebatteries. The low-power RF receiver compares detected RF energy to adetect threshold that may be increased to decrease the sensitivity ofthe low-power RF receiver and increase the lifetime of the batteries.After detecting that an RF signal is being transmitted, the low-power RFreceiver is put to sleep for a snooze time period that is longer thanthe sleep time and just slightly shorter than the time between twoconsecutive transmitted packets to further conserve battery power. Inaddition, The low-power RF receiver may be responsive to RF signalstransmitted at a different frequency than the frequency to which othercontrol devices of the load control system are responsive to limit theamount of time that the RF receiver wakes up to process incoming RFsignals and thus conserve battery power.

According to an embodiment of the present invention, a load controldevice for controlling an electrical load receiving power from a powersource in response to RF signals transmitted by an RF transmittercomprises a low-power RF receiver. The RF transmitter is adapted totransmit a number of sequential digital messages at a predeterminedtransmission rate, where each of the digital messages including the samecommand and characterized by a packet length. The load control devicecomprises an RF receiver adapted to receive at least one of thesequential digital messages, and a controller operatively coupled to theRF transceiver for receiving the at least one of the sequential digitalmessages and controlling the load in response to the received digitalmessage. The RF receiver is enabled for a sample time period todetermine if the RF transmitter is transmitting one of the digitalmessages. The RF receiver enters a sleep mode for a sleep time periodbetween consecutive sample time periods. The sleep time period of the RFreceiver is longer than the packet length of each of the digitalmessages.

According to another embodiment of the present invention, an RFcommunication system comprises an RF transmitter adapted to transmit anumber of sequential digital messages at a predetermined transmissionrate, and an RF receiver adapted to receive at least one of thesequential digital messages. Each of the digital messages including thesame command and characterized by a packet length. The RF receiver isenabled for a sampling time to determine if the RF transmitter istransmitting one of the digital messages, and enters a sleep mode for asleep time period between consecutive sample time periods. The sleeptime period of the RF receiver is longer than the packet length of eachof the digital messages.

According to another embodiment of the present invention, a wirelesssignal receiver comprises a wireless receiver circuit for detectingtransmitted signals transmitted in a predetermined number of packets,where each packet comprises the same data, there being a packet time anda time between packets substantially longer than the packet time. Thewireless signal receiver also comprises a control circuit for turning onthe wireless receiver circuit for an on-time, where the on-time issubstantially less than an off-time of the wireless receiver circuit.The on-time of the wireless receiver circuit is also substantially lessthan the packet time and the off-time between on-times being less thanthe time between packets. The off-time is selected so that within theplurality of packets, the on-time will coincide with the packet time toensure that the wireless receiver circuit detects at least one packetduring the transmission of the predetermined number of packets ifpackets are being transmitted.

In addition, a method of communicating digital messages in a loadcontrol system is also described herein. The method comprises: (1)transmitting a number of sequential digital messages at a predeterminedtransmission rate, each of the digital messages including the samecommand and characterized by a packet length; (2) enabling an RFreceiver for a sample time period to determine if the RF transmitter istransmitting one of the digital messages; and (3) putting the RFreceiver in a sleep mode for a sleep time period between consecutivesample time periods. The sleep time period of the RF receiver is longerthan the packet length of each of the digital messages.

According to another aspect of the present invention, a wireless signalreceiver circuit for detecting wireless control signals has an on/offoperation to conserve power. The wireless signal receiver circuitcomprises a control circuit, and a wireless receiver having an on statewhen it consumes power and an off state when it consumes less power thanconsumed in the on state. The on state has a duration substantiallyshorter than the off state, whereby the wireless receiver receiveswireless control signals during the on state to be processed by thecontrol circuit. The wireless control signals are sent in packets with apacket time such that there is a predefined time between packets. Thewireless receiver is operable to periodically be in the on state for asample time substantially less than the packet time to detect a wirelesscontrol signal, whereby upon detecting a first packet during the sampletime, the wireless receiver is operable to enter the off state toconserve power for an amount of time slightly less than the predefinedtime between packets, to subsequently turn on and remain on until asucceeding packet starts to be received, and to turn off after thesucceeding packet is fully received.

According to another embodiment of the present invention, abattery-powered wireless device comprises: a control circuit having anon state when it consumes power and an off state when it consumes lesspower than consumed in the on state, and a wireless receiver circuitoperable to periodically check for wireless signals. The wirelessreceiver circuit has a detect threshold wherein the wireless receivercircuit is operable to determine whether a wireless signal exceeds thedetect threshold. The receiver circuit is operable to cause the controlcircuit to be in on state in response to determining that a wirelesssignal exceeds the detect threshold. The control circuit is furtheroperable to adjust the detect threshold of the wireless receiver circuitwhereby the detect threshold can be increased to prevent noise signalsfrom causing the wireless receiver circuit to turn on the controlcircuit thereby conserving battery power.

A system for conserving battery power of a battery powered wirelesssignal receiver is also described herein. The system comprises awireless signal receiver that periodically turns on to determine if awireless signal is being transmitted and is capable of receiving on anyof multiple channels. The wireless signal receiver includes a controlcircuit that determines if the wireless signal is intended for thewireless signal receiver. The transceiver circuit retransmits thewireless signals and determines a number of transmitted wirelesssignals. If the number exceeds a threshold amount, the transceivercircuit communicates with the wireless signal receiver to change thechannel of communication to an alternate channel and retransmitswireless signals intended for the wireless signal receiver on thealternate channel, whereby the wireless signal receiver will receivefewer wireless signals on the alternate channel, thereby remaining onfor less time and reducing battery power consumption.

According to another embodiment of the present invention, a wirelesscontrol system comprises: (1) a first wireless signal receiver capableof receiving on wireless signals on a first channel; (2) a secondwireless signal receiver that periodically turns on to determine ifwireless signals are being transmitted, the second wireless signalreceiver being capable of receiving on wireless signals on a secondchannel; and (3) a transceiver circuit for retransmitting said wirelesssignals, said transceiver circuit operable to receive a first wirelesssignal on the first channel and to determine that the first wirelesssignal contains control information intended for the second wirelesssignal receiver. The transceiver circuit is operable to change itschannel of communication from the first channel to the second channel,and transmit the control information in a second wireless signal to thesecond wireless signal receiver on the second channel.

Other features and advantages of the present invention will becomeapparent from the following description of the invention that refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail in the followingdetailed description with reference to the drawings in which:

FIG. 1 is a perspective view of a motorized window treatment systemhaving a battery-powered motorized window treatment and a remote controlaccording to a first embodiment of the present invention;

FIG. 2 is a perspective view of the battery-powered motorized windowtreatment of FIG. 1 in a full-closed position;

FIG. 3 is a right side view of the battery-powered motorized windowtreatment of FIG. 1;

FIG. 4 is a front view of the battery-powered motorized window treatmentof FIG. 1;

FIG. 5 is a simplified block diagram of a motor drive unit of thebattery-powered motorized window treatment of FIG. 1;

FIGS. 6A and 6B are partial perspective views of the motor drive unitand a headrail of the motorized window treatment of FIG. 1;

FIG. 7 is simplified frequency response of an RF filter of the motordrive unit of FIG. 5;

FIG. 8 is a simplified timing diagram of an RF data transmission eventand a sampling event of the motor drive unit of FIG. 5;

FIG. 9 is a simplified flowchart of an RF signal receiving procedureexecuted by a controller of the motor drive unit of FIG. 5;

FIG. 10 is a simplified flowchart of a command procedure executedperiodically by the controller of the motor drive unit of FIG. 5;

FIG. 11 is a simplified flowchart of a motor control procedure executedperiodically by the controller of the motor drive unit of FIG. 5;

FIG. 12 is a simplified diagram of a radio-frequency load control systemincluding multiple motorized window treatments according to a secondembodiment of the present invention;

FIG. 13 is a simplified block diagram of a dimmer switch of the loadcontrol system of FIG. 12 according to the second embodiment of thepresent invention;

FIG. 14 is a simplified block diagram of a dimmer switch of the loadcontrol system of FIG. 12 according to an alternate embodiment of thepresent invention;

FIG. 15 is a simplified flowchart of an RF sampling rate selectionprocedure executed by a controller of one of the battery-poweredmotorized window treatments of FIG. 12;

FIG. 16 is a simplified graph illustrating various signal strengththresholds of one of the battery-powered motorized window treatments ofFIG. 12;

FIG. 17 is a simplified flowchart of an RF monitoring procedureperformed by a signal repeater of the load control system of FIG. 12;

FIG. 18 is a simplified flowchart of an RF signal receiving procedureperformed by a signal repeater of the load control system of FIG. 12;and

FIG. 19 is a simplified diagram of a RF load control system having twosignal repeaters coupled together via a digital communication linkaccording to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofthe preferred embodiments, is better understood when read in conjunctionwith the appended drawings. For the purposes of illustrating theinvention, there is shown in the drawings an embodiment that ispresently preferred, in which like numerals represent similar partsthroughout the several views of the drawings, it being understood,however, that the invention is not limited to the specific methods andinstrumentalities disclosed.

FIG. 1 is a perspective view of a motorized window treatment system 100having a battery-powered motorized window treatment 110 mounted in anopening 102, for example, in front of a window 104, according to a firstembodiment of the present invention. The battery-powered motorizedwindow treatment 110 comprises a covering material, for example, acellular shade fabric 112 as shown in FIG. 1. The cellular shade fabric112 has a top end connected to a headrail 114 (that extends between twomounting plates 115) and a bottom end connected to a weighting element116. The mounting plates 115 may be connected to the sides of theopening 102 as shown in FIG. 1, such that the cellular shade fabric 112is able to hang in front of the window 104, and may be adjusted betweena fully-open position P_(FULLY-OPEN) and a fully-closed positionP_(FULLY-CLOSED) to control the amount of daylight entering a room orspace. Alternatively, the mounting plates 115 of the battery-poweredmotorized window treatment 110 could be mounted externally to theopening 102 (e.g., above the opening) with the shade fabric 112 hangingin front of the opening and the window 104. In addition, thebattery-powered motorized window treatment 110 could alternativelycomprise other types of covering materials, such as, for example, aplurality of horizontally-extending slats (i.e., a Venetian or Persianblind system), pleated blinds, a roller shade fabric, or a Roman shadefabric.

The motorized window treatment system 100 comprises a radio-frequency(RF) remote control 190 for transmitting RF signals 106 to the motorizedwindow treatment 110 using, for example, a frequency-shift keying (FSK)modulation technique, to thus for control the operation of the motorizedwindow treatment. Specifically, the RF remote control 190 is operable totransmit digital messages including commands to control the motorizedwindow treatment 710 via the RF signals 106 in response to actuations ofa plurality of buttons, e.g., an open button 192, a close button 194, araise button 195, a lower button 196, and a preset button 198. Themotorized window treatment 110 controls the cellular shade fabric 112 tothe fully-open position P_(FULLY-OPEN) and the fully-closed positionP_(FULLY-CLOSED) in response to actuations of the open button 192 andthe close button 194 of the remote control 190, respectively. Themotorized window treatment 110 raises and lowers the cellular shadefabric 112 in response to actuations of the raise button 195 and thelower button 196, respectively. The motorized window treatment 110controls the cellular shade fabric 112 to a preset position P_(PRESET)in response to actuations of the preset button 198.

FIG. 2 is a perspective view and FIG. 3 is a right side view of thebattery-powered motorized window treatment 110 with the cellular shadefabric 112 in the fully-open position P_(FULLY-OPEN). The motorizedwindow treatment 110 comprises a motor drive unit 120 for raising andlowering the weighting element 116 and the cellular shade fabric 112between the fully-open position P_(FULLY-OPEN) and the fully-closedposition P_(FULLY-CLOSED). By controlling the amount of the window 104covered by the cellular shade fabric 112, the motorized window treatment110 is able to control the amount of daylight entering the room. Theheadrail 114 of the motorized window treatment 110 comprises an internalside 122 and an opposite external side 124, which faces the window 104that the shade fabric 112 is covering. The motor drive unit 120comprises an actuator 126, which is positioned adjacent the internalside 122 of the headrail 114 may may be actuated when a user isconfiguring the motorized window treatment 110. The actuator 126 may bemade of, for example, a clear material, such that the actuator mayoperate as a light pipe to conduct illumination from inside the motordrive unit 120 to thus be provide feedback to the user of the motorizedwindow treatment 110. The motor drive unit 120 is operable to determinea target position P_(TARGET) for the weighting element 116 in responseto commands included in the IR signals received from the remote control190 and to subsequently control a present position P_(PRES) of theweighting element to the target position P_(TARGET). As shown in FIG.2A, a top side 128 of the headrail 114 is open, such that the motordrive unit 120 may be positioned inside the headrail and the actuator126 may protrude slightly over the internal side 122 of the headrail.

FIG. 4 is a front view of the battery-powered motorized window treatment110 with the internal side 122 of the headrail 114 removed to show themotor drive unit 120. The motorized window treatment 110 comprises liftcords 130 that extend from the headrail 114 to the weighting element 116for allowing the motor drive unit 120 to raise and lower the weightingelement. The motor drive unit 120 includes an internal motor 150 (FIG.5) coupled to drive shafts 132 that extend from the motor on each sideof the motor and are each coupled to a respective lift cord spool 134.The lift cords 130 are windingly received around the lift cord spools134 and are fixedly attached to the weighting element 116, such that themotor drive unit 120 is operable to rotate the drive shafts 132 to raiseand lower the weighting element. The motorized window treatment 110further comprises two constant-force spring assist assemblies 135, whichare each coupled to the drive shafts 132 adjacent to one of the two liftcord spools 134. Each of the lift cord spools 134 and the adjacentconstant-force spring assist assembly 135 are housed in a respectivelift cord spool enclosure 136 as shown in FIG. 3. Alternatively, themotor drive unit 120 could be located at either end of the headrail 114and the motorized window treatment 110 could comprise a single driveshaft that extends along the length of the headrail and is coupled toboth of the lift cord spools 134.

The battery-powered motorized window treatment 110 also comprises aplurality of batteries 138 (e.g., four D-cell batteries), which areelectrically coupled in series. The seris-combination of the batteries138 is coupled to the motor drive unit 120 for powering the motor driveunit. The batteries 138 are housed inside the headrail 114 and thus outof view of a user of the motorized window treatment 110. Specifically,the batteries 138 are mounted in two battery holders 139 located insidethe headrail 114, such that there are two batteries in each batteryholder as shown in FIG. 4. According to the embodiments of the presentinvention, the batteries 138 provide the motorized window treatment 110with a practical lifetime (e.g., approximately three years), and aretypical “off-the-shelf” batteries that are easy and not expensive toreplace. Alternatively, the motor drive unit 120 could comprise morebatteries (e.g., six or eight) coupled in series or batteries of adifferent kind (e.g., AA batteries) coupled in series.

FIG. 5 is a simplified block diagram of the motor drive unit 120 of thebattery-powered motorized window treatment 110. The motor drive unit 120comprises a controller 152 for controlling the operation of the motor150, which may comprise, for example, a DC motor. The controller 152 maycomprise, for example, a microprocessor, a programmable logic device(PLD), a microcontroller, an application specific integrated circuit(ASIC), a field-programmable gate array (FPGA), or any suitableprocessing device or control circuit. The controller 152 is coupled toan H-bridge motor drive circuit 154 for driving the motor 150 via a setof drive signals V_(DRIVE) to control the weighting element 116 and thecellular shade fabric 112 between the fully-open position P_(FULLY-OPEN)and the fully-closed position P_(FULLY-CLOSED). The controller 152 isoperable to rotate the motor 150 at a constant rotational speed bycontrolling the H-bridge motor drive circuit 154 to supply a pulse-widthmodulated (PWM) drive signal having a constant duty cycle to the motor.The controller 152 is able to change the rotational speed of the motor150 by adjusting the duty cycle of the PWM signal applied to the motorand to change the direction of rotation of the motor by changing thepolarity of the PWM drive signal applied to the motor.

The controller 152 receives information regarding the rotationalposition and direction of rotation of the motor 150 from a rotationalposition sensor, such as, for example, a transmissive optical sensorcircuit 155. The rotational position sensor may also comprise othersuitable position sensors or sensor arrangements, such as, for example,Hall-effect, optical, or resistive sensors. The controller 152 isoperable to determine a rotational position of the motor 150 in responseto the transmissive optical sensor circuit 155, and to use therotational position of the motor to determine a present positionP_(PRES) of the weighting element 116. The controller 152 may comprisean internal non-volatile memory (or alternatively, an external memorycoupled to the controller) for storage of the present position P_(PRES)of the shade fabric 112, the fully open position P_(FULLY-OPEN), and thefully closed position P_(FULLY-CLOSED). The operation of the H-bridgemotor drive circuit 154 and the use of sensor devices to track thedirection and speed of the motor drive unit 120 is described in greaterdetail in commonly-assigned U.S. Pat. No. 5,848,634, issued Dec. 15,1998, entitled MOTORIZED WINDOW SHADE SYSTEM, and commonly-assigned U.S.Pat. No. 6,497,267, issued Dec. 24, 2002, entitled MOTORIZED WINDOWSHADE WITH ULTRAQUIET MOTOR DRIVE AND ESD PROTECTION, the entiredisclosures of which are herein incorporated by reference.

A user of the window treatment system 100 is able to adjust the positionof the weighting element 116 and the cellular shade fabric 112 by usingthe remote control 190 to transmit commands to the motor drive unit 120via the RF signals 106. The motor drive unit 120 comprises an RFreceiver 166 coupled to an antenna 168 (e.g., a wire antenna) forreceiving the RF signals 106. The antenna 168 is coupled to the RFreceiver 166 via a surface acoustic wave (SAW) filter 169 (e.g., partnumber B3580 as manufactured by Epcos AG), which acts to filter RF noiseas will be described in greater detail below. The RF receiver 166 isoperable to provide an RF data control signal V_(RF-DATA) representativeof the received RF signals 106 to a controller 152, such that thecontroller is operable to control the H-bridge motor drive circuit 154in response to the received signals.

FIGS. 6A and 6B are partial perspective views of the motor drive unit120 and the headrail 114 of the motorized window treatment 110. Theantenna 168 is adapted to extend from the motor drive unit 168 and isreceived in an elongated antenna wire carrier 170. As shown in FIG. 6A,the antenna wire carrier 170 may be located in a first positionimmediately adjacent the motor drive unit 120 above the external side124 of the headrail 114. The antenna wire carrier 170 may be removedfrom the first position and re-located into a second position in whichthe antenna 168 is slightly offset (e.g., by a distance of approximately0.4 inch) from the motor drive unit 120 as shown in FIG. 6B. The antennawire carrier 170 comprises clips 172 that are adapted to snap onto thetop edge of the external side 124 of the headrail 114 in the secondposition. The antenna wire carrier 170 provides a mechanical means foradjusting the RF sensitivity of the RF receiver 166 and thus the powerconsumed by the RF receiver 166. When the antenna wire carrier 170 islocated in the second position (as shown in FIG. 6B), the RF receiver166 has an increased RF sensitivity (e.g., by approximately 3 dB), andis thus operable to receive more RF signals 106 than if the antenna wirecarrier was located in the first position (as shown in FIG. 6A).However, the increased RF sensitivity means that the RF receiver 166will consume more power. Therefore, the antenna wire carrier 170 may bemoved to the first position in which the RF receiver 166 has a reducedRF sensitivity, but consumes less power.

As shown in FIG. 5, the motor drive unit 120 receives power from theseries-coupled batteries 138, which provide a battery voltage V_(BATT).For example, the batteries 138 may comprise D-cell batteries havingrated voltages of approximately 1.5 volts, such that the battery voltageV_(BATT) has a magnitude of approximately 6 volts. The H-bridge motordrive circuit 154 receives the battery voltage V_(BATT) for driving themotor 150. In order to preserve the life of the batteries 138, thecontroller 152 may be operable to operate in a sleep mode when the motor150 is idle.

The motor drive unit 120 further comprises a power supply 156 (e.g., alinear regulator) that receives the battery voltage V_(BATT) andgenerates a DC supply voltage V_(CC) for powering the controller 152 andother low-voltage circuitry of the motor drive unit. The controller 152is coupled to the power supply 156 and generates a voltage adjustmentcontrol signal V_(ADJ) for adjusting the magnitude of the DC supplyvoltage V_(CC) between a first nominal magnitude (e.g., approximately2.7 volts) and a second increased magnitude (e.g., approximately 3.3volts). The power supply 156 may comprise, for example, an adjustablelinear regulator having one or more feedback resistors that are switchedin and out of the circuit by the controller 152 to adjust the magnitudeof the DC supply voltage V_(CC). The controller 152 may adjust themagnitude of the DC supply voltage V_(CC) to the second increasedmagnitude while the controller is driving the motor drive circuit 154 torotate the motor 150 (since the controller may require an increasedsupply voltage to drive the motor drive circuit). The controller 152adjusts the magnitude of the DC supply voltage V_(CC) to the firstnominal magnitude when the controller is not controlling the motor drivecircuit 154 to rotate the motor 150 (e.g., when the controller is in thesleep mode). The magnitude of the idle currents drawn by the controller152, the IR receiver 166, and other low-voltage circuitry of the motordrive unit 120 may be significantly smaller when these circuits arepowered by the first nominal magnitude of the DC supply voltage V_(CC).

The controller 152 is operable to determine that the magnitude of thebattery voltage V_(BATT) is getting low and to operate in a low-batterymode when the magnitude of the battery voltage V_(BATT) drops below afirst predetermined battery-voltage threshold V_(B-TH1) (e.g.,approximately 1.0 volts per battery). For example, the controller 152may control the motor drive circuit 154 so that the motor 150 isoperated at a reduced speed (e.g., at half speed) to conserve batterypower when the controller 152 is operating in the low-battery mode. Thiswould serve as an indication to a consumer that the battery voltageV_(BATT) is low and the batteries 138 need to be changed.

When the magnitude of the battery voltage V_(BATT) drops below a secondpredetermined battery-voltage threshold V_(B-TH2) (less than the firstpredetermined battery-voltage threshold V_(B-TH1), e.g., approximately0.9 V per battery) while operating in the low-battery mode, thecontroller 152 may shut down electrical loads in the motor drive unit120 (e.g., by disabling the IR receiver 166 and other low-voltagecircuitry of the motor drive unit) and prevent movements of the cellularshade fabric 112 except to allow for at least one additional movement ofthe cellular shade fabric to the fully-open position P_(FULLY-OPEN).Having the cellular shade fabric 112 at the fully-open positionP_(FULLY-OPEN) allows for easy replacement of the batteries. The secondpredetermined battery-voltage threshold V_(B-TH2) may be sized toprovide enough reserve energy in the batteries 138 to allow for the atleast one additional movement of the cellular shade fabric 112 and theweighting element 116 to the fully-open position P_(FULLY-OPEN).

When the magnitude of the battery voltage V_(BATT) drops below a thirdpredetermined battery-voltage threshold V_(B-TH3) (less than the secondpredetermined battery-voltage threshold V_(B-TH2), e.g., approximately0.8 V per battery), the controller 152 may be operable to shut itselfdown such that no other circuits in the motor drive unit 120 consume anypower in order to protect against any potential leakage of the batteries138.

The motor drive unit 120 comprises an alternate (or supplemental) powersource, such as a backup battery, e.g., a long-lasting battery (notshown), which generates a backup supply voltage V_(BACKUP) (e.g.,approximately 3.0 volts) for powering the controller 152. The alternatepower source provides the controller 152 with power when the batteries138 are removed for replacement, or otherwise depleted, such that theposition data relating to the position of the window treatment that isstored in the memory of the controller 152 is maintained. Alternatively,a large bus capacitor or an ultra-capacitor can be coupled to thecontroller 152 (rather than the backup battery), so that even when thebatteries 138 are removed for replacement, an adequate charge willremain in the bus capacitor or ultra capacitor to maintain adequatevoltage to keep the controller 152 charged for the period of timenecessary to replace batteries 138 and thereby prevent loss of storeddata in the memory of the controller.

These embodiments allow the motor drive unit 120 to keep track of theposition of the weighting element 116 of the window treatment 110 evenwhen the batteries 138 are removed and the window treatment is manuallyoperated (i.e., pulled). In such embodiments, the controller 152continues to receive signals from transmissive optical sensor circuit155, even when the batteries 138 are removed. Because it remainspowered, the controller 152 will continue to calculate the position ofthe window treatment 110 when manually adjusted. It should be pointedout that the window treatment 110 of the present invention allows a userat any time to manually adjust the position of the window treatment, andthat the position of the window treatment is always calculated both whenthe window treatment is moved by the motor or manually.

As shown in FIG. 5, the motor drive unit 120 comprises an internaltemperature sensor 160 that is located adjacent the internal side 122 ofthe headrail 114 (i.e., a room-side temperature sensor), and a externaltemperature sensor 162 that is located adjacent the external side 124 ofthe headrail (i.e., a window-side temperature sensor). The room-sidetemperature sensor 160 is operable to measure an interior temperatureinside the room in which the motorized window treatment 110 isinstalled, while the external temperature sensor 162 is operable tomeasure an exterior temperature between the headrail 114 and the window104. The motor drive unit 120 further comprises a photosensor 164, whichis located adjacent the external side 124 of the headrail 114, and isdirected to measure the amount of sunlight that may be shining on thewindow 104. Alternatively, the exterior (window-side) temperature sensor162 may be implemented as a sensor label (external to the headrail 114of the battery powered motorized window treatment 110) that is operableto be affixed to an inside surface of a window. The sensor label may becoupled to the motor drive unit 120 through low voltage wiring (notshown).

The controller 152 receives inputs from the internal temperature sensor160, the external temperature sensor 162, and the photosensor 164. Thecontroller 152 may operate in an eco-mode to control the position of theweighting element 116 and the cellular shade fabric 112 in response tothe internal temperature sensor 160, the external temperature sensor162, and the photosensor 164, so as to provide energy savings. Whenoperating in the eco-mode, the controller 152 adjusts the amount of thewindow 104 covered by the cellular shade fabric 112 to attempt to saveenergy, for example, by reducing the amount of electrical energyconsumed by other control systems in the building in which the motorizedwindow treatment 110 is installed. For example, the controller 152 mayadjust the present position P_(PRES) of the weighting element 116 tocontrol the amount of daylight entering the room in which the motorizedwindow treatment 110 is installed, such that lighting loads in the roommay be turned off or dimmed to thus save energy. In addition, thecontroller 152 may adjust the present position P_(PRES) of the weightingelement 116 to control the heat flow through the window 104 in order tolighten the load on a heating and/or cooling system, e.g., a heating,air-conditioning, and ventilation (HVAC) system, in the building inwhich the motorized window treatment 110 is installed.

The motorized window treatment 110 and the RF remote control 190 may beeasily programmed, such that the motorized window treatment 110 isresponsive to actuations of the buttons 192-198 of the remote control190. First, the user may associate the remote control 190 with themotorized window treatment 110 by actuating the actuator 126 on themotor drive unit 120 and then pressing and holding, for example, theclose button 194 on the remote control for a predetermined amount oftime (e.g., approximately five seconds). After the remote control 190 isassociated with the motorized window treatment 110, the motorized windowtreatment is responsive to the RF signals 106 transmitted by the remotecontrol. The user may program the preset position P_(PRESET) of themotorized window treatment 110 by actuating the raise and lower buttons195, 196 of the remote control 190 to adjust the position of theweighting element 116 to the desired preset position, and then pressingand holding the preset button 198 for the predetermined amount of time.

The user may also use the remote control 190 to program the upper andlower limits (i.e., the fully-open position P_(FULLY-OPEN) and thefully-closed position P_(FULLY-CLOSED)) of the motorized windowtreatments 110. To enter a limit programming mode, the user actuates theactuator 126 on the motor drive unit 120, and then simultaneouslypresses and holds the open button 192 and the raise button 195 of theremote control 190 for the predetermined amount of time (i.e.,approximately five seconds). To program the lower limit, the useractuates the raise and lower buttons 195, 196 of the remote control 190to adjust the position of the weighting element 116 to the desiredfully-closed position P_(FULLY-CLOSED), and then presses the closebutton 194 for the predetermined amount of time. To program the upperlimit, the user actuates the raise and lower buttons 195, 196 of theremote control to adjust the position of the weighting element 116 tothe desired fully-open position P_(FULLY-OPEN), and then presses theopen button 192 for the predetermined amount of time. The user can thenpress and hold the open button 192 and the raise button 195 of theremote control 190 for the predetermined amount of time to exit thelimit programming mode.

The RF receiver 166 and the controller 152 are both able to be put in asleep mode (i.e., low-power mode) to conserve battery power. During thesleep mode, the RF receiver 166 is operable to wake-up periodically tosample (e.g., listen for) RF energy (i.e., RF signals 106) as will bedescribed in greater detail below. In the event that the RF receiver 166does detect the presence of any RF signals 106, the RF receiver isoperable to wake up the controller 152 via an RF wake up signal V_(RF)_(—) _(WAKE), such that the controller can begin processing the receivedRF signal. In particular, the RF receiver 166 wakes up the controller152 in response to detecting any RF energy within a particular frequencyband. Each time that the controller 152 wakes up in response to the RFwake up signal V_(RF) _(—) _(WAKE), additional power is consumed by thecontroller (since the controller is fully powered when awake). Thisadditional power consumption reduces the life of the batteries 138, andas a result, it is optimal that the RF receiver 166 only wake up thecontroller 152 when necessary.

FIG. 7 shows an example of a simplified frequency response of the SAWfilter 169. Frequency 180 illustrates an example frequency of the RFsignals 106. A frequency response 182 illustrates the response of onlythe antenna 168 and the RF receiver 166 (i.e., the response without theSAW filter 169). As shown in FIG. 7, the frequency response 182 spans awide range of frequencies (e.g., up to an 80 MHz band). As a result, theRF receiver 166 may be responsive to an interference event 184. Inparticular, the RF receiver 166 (without the presence of the SAW filter169) will detect the presence of the interference event 184, and as aresult, will cause the controller 152 to wake up via the RF wake upsignal V_(RF) _(—) _(WAKE). As the controller 152 begins to process theinterference event 184, the controller will appropriately disregard thisinterference event as it will recognize that it is not an RF signal 106.However as mentioned above, the controller 152 consumes additional powerto process the interference event 184, and this negatively impacts thelife of the batteries 138. FIG. 7 also illustrates a SAW frequencyresponse 186 which spans a much narrower band of frequencies thanfrequency response 182. In particular, the SAW frequency response 186does not encompass the interference event 184. As a result, the SAWfilter 169 filters interference events (e.g., such as interference event184), and this allows the controller 152 to not wake up unnecessarily,thus further conserving the life of the batteries 138.

FIG. 8 is a simplified timing diagram of a data transmission eventtransmitted by the RF remote control 190 to the motorized windowtreatment 110 and a sampling event of the RF receiver 166 of the motordrive unit 120. The remote control 190 transmits packets of data (e.g.,the control information) via the RF signals 106 with each packet havinga packet time period T_(PACKET) (e.g, approximately 5 msec). Each packetof data is typically transmitted multiple times (e.g., up to twelvetimes) during a given data transmission event. Between each packet ofdata, there is a packet break time period T_(PKT) _(—) _(BRK) (e.g.,approximately 75 ms), such that the remote control transmits digitalmessages at a transmission rate of approximately 12.5 packets persecond. The RF receiver 166 of the motor drive unit 120 is operable towake up and listen for any RF signals 106 during an RF sampling timeperiod T_(SMPL-RF). If no RF signals 106 are detected during the RFsample time period T_(SMPL-RF), then the RF receiver 166 goes to sleepfor an RF sleep time period T_(SLP-RF), such that the RF receiversamples the RF data at a sampling period T_(SAMPLE). Alternatively, thebreak time period T_(PKT) _(—) _(BRK) could not be a fixed value, butcould be a varying or random time between each of the transmittedpackets.

The RF sample time period T_(SMPL-RF) and the RF sleep time periodT_(SLP-RF) of the RF receiver 166 are sized appropriately to ensure thatthe RF sample time period T_(SMPL-RF) coincides with at least one packetof a predetermined number of consecutive packets of a data transmissionevent. As a result, the RF sleep time period T_(SLP-RF) of the RFreceiver 166 can be much longer than the packet time period T_(PACKET).In addition, the RF sample time period T_(SMPL-RF) can be significantlyshorter than the packet time period T_(PACKET). Accordingly, the RFreceiver 166 is operable to sleep for longer periods of time than priorart RF receivers, thus extending the lifetime of the batteries 138 ofthe motor drive unit 120. For example, the RF sample time periodT_(SMPL-RF) and the RF sleep time period T_(SLP-RF) may be sized to beapproximately 0.1 msec and 17.8 msec, respectively, to ensure that theRF sample time period T_(SMPL-RF) coincides with at least one packet offive consecutive packets of a data transmission event.

Four packets 200, 202, 204, and 206 of a data transmission event areshown in FIG. 8. At time t₀, the remote control 190 begins to transmitthe first packet 200 via the RF signals 106. The first packet 200 is notreceived by the RF receiver 166 because the packet is transmitted duringthe RF sleep time period T_(SLP-RF) (i.e., while the RF receiver issleeping). In other words, the transmission of packet 200 does notcoincide with an RF sampling event 210 of the RF receiver. Similarly,the second packet 202 transmitted at time t₁ is not received by the RFreceiver 166 because the packet is transmitted during the RF sleep timeand does not coincide with one of the RF sampling events 210 of the RFreceiver 166.

At time t₂, the third packet 204 is transmitted and is detected by theRF receiver 166, such that the RF receiver wakes up the controller 152.Since the controller 152 wakes up in the middle of the transmission ofthe third packet 204 (i.e., has missed the beginning of the transmissionof the third packet), the controller is unable to properly process thedata contained within the third packet. However, the controller 152 isoperable to process the third packet 204 sufficiently to determine thata fourth packet 206 will be transmitted after the packet break timeperiod T_(PKT) _(—) _(BRK). Accordingly, the controller 152 and the RFreceiver 166 are operable to enter the sleep mode for a snooze timeperiod T_(SNOOZE), which may be approximately equal to or slightly lessthan the packet break time period T_(PKT) _(—) _(BRK). As shown in FIG.8, the snooze time period T_(SNOOZE) expires just before time t₃, whenthe fourth packet 206 is transmitted. In other words, the duration ofthe snooze time period T_(SNOOZE) is short enough to ensure that the RFreceiver 166 is awake in time to receive the complete transmission ofthe fourth packet 206.

When the snooze time period T_(SNOOZE) expires, the RF receiver 166 andthe controller 152 wake up, and the RF transceiver begins to listen toRF signals 106 for at least the RF sample time period T_(SMPL-RF).Because the RF receiver 166 and the controller 152 are awake at time t₃when the remote control 190 begins to transmit the fourth packet 206,the receiver is able to receive the entire packet. The receiver 166remains on for an RF on time period T_(ON-RF) and is operable to receivethe entire packet 206 during an RF receiving event 212, such that thecontroller 152 is able to properly process the packet 206 of data. Thus,because the RF receiver 166 and the controller 152 go back to sleepduring the snooze time period T_(SNOOZE) (and do not stay awake andfully powered while waiting for the next packet to be transmitted), thelife of the batteries 138 is further conserved.

FIG. 9 is a simplified flowchart of an RF signal receiving procedure 300executed by the controller 152 after being awakened in response to theRF wake up signal V_(RF) _(—) _(WAKE) at step 310. The controller 152uses a SNOOZE flag to keep track of when the RF receiver 166 has beenput to sleep for the snooze time period T_(SNOOZE). If the SNOOZE flagis not set at step 312 (i.e., the RF receiver 166 has not been put tosleep for the snooze time period T_(SNOOZE)) and the controller 152 doesnot detect an indication that an RF signal is present at step 314, thecontroller 152 simply goes back to sleep at step 316 and the RF signalreceiving procedure 300 exits. However, if the controller 152 detects anRF signal at step 314, the controller sets the SNOOZE flag at step 318,and puts the RF receiver to sleep for the snooze time period T_(SNOOZE)at step 320. The controller 152 then goes back to sleep at step 316,before the RF signal receiving procedure 300 exits.

If the SNOOZE flag is set at step 312 (i.e., the RF receiver 166 hasbeen put to sleep for the snooze time period T_(SNOOZE)), the controller152 first clears the SNOOZE flag at step 322 and then gets ready toreceive a digital message. If the RF receiver 766 is not receiving thestart of a digital message at step 324, the controller 152 puts the RFreceiver to sleep for the RF sleep time period T_(SLP-RF) at step 326and goes back to sleep at step 316, before the RF signal receivingprocedure 300 exits. However, if the RF receiver 166 is receiving thestart of a digital message at step 324, the controller 152 stores thereceived message in a receive (RX) buffer at step 328 and puts the RFreceiver to sleep for the RF sleep time period T_(SLP-RF) at step 330.The RF signal receiving procedure 300 exits without the controller 152being put back to sleep. The controller 152 will go back to sleep afterprocessing the received digital message.

FIG. 10 is a simplified flowchart of a command procedure 400 executedperiodically by the controller 152. If there is not a command in the RXbuffer at step 410, the command procedure 400 simply exits. However, ifthere is an open command in the RX buffer at step 412, the controller152 sets the target position P_(TARGET) equal to the fully-open positionP_(FULLY-OPEN) at step 414, before the command procedure 400 exits. Ifthe received command is a close command at step 416, the controller 152sets the target position P_(TARGET) equal to the fully-closed positionP_(FULLY-CLOSED) at step 418 and the command procedure 400 exits. If thereceived command is a raise command at step 420 or a lower command atstep 424, the controller 152 respectively increases the target positionP_(TARGET) by a predetermined increment ΔP at step 422 or decreases thetarget position P_(TARGET) by the predetermined increment ΔP at step426, before the command procedure 400 exits.

FIG. 11 is a simplified flowchart of a motor control procedure 500executed periodically by the controller 152 (e.g., every two msec). Ifthe motor 150 is not presently rotating at step 510 and the presentposition P_(PRES) is equal to the target position P_(TARGET) at step512, the motor control procedure 500 simply exits without controllingthe motor. However, if the motor 150 is not presently rotating at step510 and the present position P_(PRES) is not equal to the targetposition P_(TARGET) at step 512, the controller 152 controls the voltageadjustment control signal V_(ADJ) to adjust the magnitude of the DCsupply voltage V_(CC) to the increased magnitude (i.e., approximately3.3 volts) at step 514. The controller 152 then begins to control theH-bridge drive circuit 154 to drive the motor 150 appropriately at step516, so as to move the weighting element 116 towards the target positionP_(TARGET). If the motor 150 is presently rotating at step 510, but thepresent position P_(PRES) is not yet equal to the target positionP_(TARGET) at step 518, the controller 512 continues to drive the motor150 appropriately at step 520 and the motor control procedure 500 exits.If the motor 150 is presently rotating at step 510 and the presentposition P_(PRES) is now equal to the target position P_(TARGET) at step518, the controller 152 stops driving the motor at step 522 and controlsthe voltage adjustment control signal V_(ADJ) to adjust the magnitude ofthe DC supply voltage V_(CC) to the nominal magnitude (i.e.,approximately 2.7 volts) at step 524.

As previously mentioned, the controller 152 operates in a low-batterymode when the magnitude of the battery voltage V_(BATT) is getting low.Specifically, if the magnitude of the battery voltage V_(BATT) hasdropped below the first battery-voltage threshold V_(B-TH1) at step 526,the controller 152 begins at step 528 to operate in the low-battery modeduring which the controller 152 will operate the motor at a reducedspeed (i.e., at half speed). If the magnitude of the battery voltageV_(BATT) is less than or equal to the second battery-voltage thresholdV_(B-TH2) at step 530, the controller 152 allows for one last movementof the cellular shade fabric 112 and the weighting element 116 to thefully-open position P_(FULLY-OPEN) by setting a FINAL_MOVE flag inmemory at step 532. At step 534, the controller 152 shuts down allunnecessary loads of the motor drive unit 120 (e.g., the externaltemperature sensor 162, the photosensor 164, the internal temperaturesensor 160, and the IR receiver 166) and prevents the motor 150 frommoving the cellular shade fabric 112 and the weighting element 116except for one last movement to the fully-open position P_(FULLY-OPEN).If the magnitude of the battery voltage V_(BATT) is less than or equalto the third battery-voltage threshold V_(B-TH3) at step 536, thecontroller 152 shuts itself down at step 538 such that no other circuitsin the motor drive unit 120 consume any power to thus protect againstany potential leakage of the batteries 138. Otherwise, the motor controlprocedure 500 exits.

The battery-powered motorized window treatment 110 is described ingreater detail in U.S. patent application Ser. No. 13/415,084, filedMar. 8, 2012, entitled MOTORIZED WINDOW TREATMENT, the entiredisclosures of which are hereby incorporated by reference. While thebattery-powered motorized window treatment 110 of the first embodimentcomprises the cellular shade fabric 112, the low-power RF receiver 166could alternatively be used in other types of motorized windowtreatments, such as, for example, roller shades, draperies, Romanshades, Venetian blinds, and tensioned roller shade systems. An exampleof a roller shade system is described in greater detail incommonly-assigned U.S. Pat. No. 6,983,783, issued Jan. 10, 2006,entitled MOTORIZED SHADE CONTROL SYSTEM, the entire disclosure of whichis hereby incorporated by reference. An example of a drapery system isdescribed in greater detail in commonly-assigned U.S. Pat. No.6,994,145, issued Feb. 7, 2006, entitled MOTORIZED DRAPERY PULL SYSTEM,the entire disclosure of which is hereby incorporated by reference. Anexample of a Roman shade system is described in greater detail incommonly-assigned U.S. patent application Ser. No. 12/784,096, filedMar. 20, 2010, entitled ROMAN SHADE SYSTEM, the entire disclosure ofwhich is hereby incorporated by reference. An example of a Venetianblind system is described in greater detail in commonly-assigned U.S.patent application Ser. No. 13/233,828, filed Sep. 15, 2011, entitledMOTORIZED VENETIAN BLIND SYSTEM, the entire disclosure of which ishereby incorporated by reference. An example of a tensioned roller shadesystem is described in greater detail in commonly-assigned U.S. Pat. No.8,056,601, issued Nov. 15, 2011, entitled SELF-CONTAINED TENSIONEDROLLER SHADE SYSTEM, the entire disclosure of which is herebyincorporated by reference.

FIG. 12 is a simplified diagram of a radio frequency (RF) load controlsystem 600 having multiple battery-powered motorized window treatments610 according to a second embodiment of the present invention. Thebattery-powered motorized window treatments 610 of the second embodimenteach have a very similar structure as the battery-powered motorizedwindow treatment 110 of the first embodiment (as shown in FIG. 5).However, each of the motorized window treatments 610 of the secondembodiment comprises a motor drive unit 620 having an RF transceiver(not shown) rather than the RF receiver 166, such that the motorizedwindow treatments are operable to both transmit and receive RF signals606. The control devices of the load control system 600 are operable totransmit packets using a packet time period T_(PACKET) (e.g.,approximately msec) and a packet break time period T_(PKT) _(—) _(BRK)(e.g., approximately 75 msec) as in the first embodiment.

As in the first embodiment, each motorized window treatment 610 isoperable to enable the RF transceiver at a sampling period T_(SAMPLE)(e.g., approximately 17.8 msec) to detect if an RF signal 602 ispresently being transmitted. Each motorized window treatment 610 isoperable put the RF transceiver to sleep for an RF sleep time periodT_(SLP-RF) that is much longer than the packet time period T_(PACKET)(e.g., approximately 17.3 msec) and to enable an RF transceiver for theRF sample time period T_(SMPL-RF) that is much shorter than the packettime period T_(PACKET) (e.g., approximately 5 msec) so as to conservebattery power. The motorized window treatments 610 execute an RF signalreceiving procedure similar to the RF signal receiving procedure 300 ofthe first embodiment as shown in FIG. 9. However, the motorized windowtreatments 610 of the second embodiment do not put the RF transceiver tosleep for the snooze time period T_(SNOOZE) after detecting an RF signalduring the RF sample time period T_(SMPL-RF). Rather, the motorizedwindow treatments 610 of the second embodiment simply remain on afterdetecting an RF signal during the RF sample time period T_(SMPL-RF).

As shown in FIG. 12, the load control system 600 also comprises alighting control device, e.g., a wall-mountable dimmer switch 630, whichis coupled to an alternating-current (AC) power source 604 via a linevoltage wiring 605. The dimmer switch 630 is operable to adjust theamount of power delivered to a lighting load 632 to control the lightingintensity of the lighting load. The dimmer switch 630 is operable totransmit and receive digital messages via the RF signals 606 and isoperable to adjust the lighting intensity of the lighting load 632 inresponse to the digital messages received via the RF signals.

FIG. 13 is a simplified block diagram of the dimmer switch 630 accordingto the second embodiment of the present invention. The dimmer switch 630comprises a hot terminal H that is adapted to be coupled to the AC powersource 604 and a dimmed hot terminal DH adapted to be coupled to thelighting load 632. The dimmer switch 630 comprises a controllablyconductive device 710 coupled in series electrical connection betweenthe AC power source 1002 and the lighting load 632 for control of thepower delivered to the lighting load. The controllably conductive device710 may comprise any suitable type of bidirectional semiconductorswitch, such as, for example, a triac, a field-effect transistor (FET)in a rectifier bridge, or two FETs in anti-series connection. The dimmerswitch 630 comprises a controller 714 that is operatively coupled to acontrol input of the controllably conductive device 710 via a gate drivecircuit 712 for rendering the controllably conductive device conductiveor non-conductive to thus control the amount of power delivered to thelighting load 632. The controller 714 is, for example, a microprocessor,but may alternatively be any suitable processing device, such as aprogrammable logic device (PLD), a microcontroller, or an applicationspecific integrated circuit (ASIC).

The controller 714 receives inputs from actuators 716 for controllingthe present intensity of the lighting load 632, and controls one or morevisual indicators 718 for providing feedback of the present intensity ofthe lighting load. The controller 714 receives a control signalrepresentative of the zero-crossing points of the AC mains line voltageof the AC power source 604 from a zero-crossing detector 720. Thecontroller 714 is operable to render the controllably conductive device710 conductive and non-conductive at predetermined times relative to thezero-crossing points of the AC waveform using a phase-control dimmingtechnique. The dimmer switch 630 further comprises a memory 722 forstoring the present intensity of the lighting load 632 as well as otheroperating characteristics of the dimmer switch. The memory 722 may beimplemented as an external integrated circuit (IC) or as an internalcircuit of the controller 714.

The dimmer switch 630 also comprises a radio-frequency (RF) transceiver724 and an antenna 726 for transmitting and receiving digital messagesvia RF signals. The controller 714 is operable to control thecontrollably conductive device 710 to adjust the intensity of thelighting load 632 in response to the digital messages received via theRF signals. The controller 714 may also transmit feedback informationregarding the amount of power being delivered to the lighting load 632via the digital messages included in the RF signals. The RF transceiver724 could alternatively be implemented as an RF receiver for onlyreceiving RF signals. To check for RF signals that are beingtransmitted, the controller 714 enables the RF transceiver 724 at asampling period T_(SAMPLE) (e.g., approximately 17.8 msec) using, forexample, a duty cycle of approximately 50%, such that the dimmer switch630 enables the RF transceiver for an RF sample time period T_(SMPL-RF)(e.g., approximately 8.9 msec), and puts the RF transceiver to sleep foran RF sleep time period T_(SLP-RF) (e.g., approximately 8.9 msec).Accordingly, the RF sleep time period T_(SLP-RF) used by the dimmerswitch 630 is longer than the packet time period T_(PACKET) so as toreduce the total power consumed by the dimmer switch 630.

The dimmer switch 630 comprises a power supply 728 for generating adirect-current (DC) supply voltage V_(CC) for powering the controller714, the memory 722, the RF transceiver 724, and the other low-voltagecircuitry of the dimmer switch. Since the dimmer switch 630 does nothave a connection to the neutral side of the AC power source 604, thepower supply 724 is operable to conduct a charging current through thelighting load 632 to generate the DC supply voltage V_(CC). Somelighting loads may be susceptible to flickering and other undesirablebehavior if the magnitude of the charging current conducted through thelighting load is too large. Accordingly, the use of the RF sleep timeperiod T_(SLP-RF) that is longer than the packet time period T_(PACKET)by the controller 714 helps to reduce the magnitude of the chargingcurrent conducted through the lighting load 632 and thus helps to avoidflickering in the lighting load.

FIG. 14 is a simplified block diagram of a dimmer switch 630′ accordingto an alternate embodiment of the present invention. The dimmer switch630′ is very similar to the dimmer switch 630 of the second embodiment.However, the dimmer switch 630′ has an earth ground terminal GND that isadapted to be coupled to earth ground. The zero-crossing detector 620and the power supply 628 of the dimmer switch 630′ are coupled betweenthe hot terminal H and the earth ground terminal GND (rather than thedimmed hot terminal DH). Accordingly, the power supply 728 conducts thecharging current through the earth ground terminal GND (rather than thelighting load 632). The magnitude of the total current conducted throughthe earth ground terminal GND by the dimmer switch 630′ is limited bystandards and regulations in most countries. The use of the RF sleeptime period T_(SLP-RF) that is longer than the packet time periodT_(PACKET) by the controller 714 helps to reduce the magnitude of thecharging current conducted through the earth ground terminal GND.

Referring back to FIG. 12, the load control system 600 further comprisesa wall-mounted button keypad 640 and a battery-powered tabletop buttonkeypad 642. The wall-mounted button keypad 640 is powered from the ACpower source 604 via the line voltage wiring 605, and the tabletopbutton keypad 642 is a battery-powered device. Both of the keypads 640,642 transmit digital messages to the dimmer switch 630 via the RFsignals 606 in order to provide for remote control of the lighting load632. In addition, each of the keypads 640, 642 is operable to receivedigital status messages via the RF signals 606 from the dimmer switch630 in order to display the status (i.e., on/off state and/or intensitylevel) of the lighting load 632. The load control system 600 furthercomprises a battery-powered remote control 644 which is operable totransmit digital messages to the dimmer switch 630 via the RF signals606 in order to provide for remote control of the lighting load 632. Thewall-mounted button keypad 640, the tabletop button keypad 642, and theremote control 644 are also operable to adjust the present positionP_(PRES) of the battery-powered motorized window treatments 610 bytransmitting digital messages via the RF signals 606. In addition, thebattery-powered motorized window treatments 610 may be operable totransmit status information to the wall-mounted keypad 640 and tabletopbutton keypad 642.

The load control system 600 further comprises a battery-powered wirelessoccupancy sensor 646 for detecting an occupancy condition (i.e., thepresence of an occupant) or a vacancy condition (i.e., the absence of anoccupant) in the space in which the occupancy sensor is mounted. Theoccupancy sensor 646 is operable to wirelessly transmit digital messagesvia the RF signals 606 to the dimmer switch 630 in response to detectingthe occupancy condition or the vacancy condition in the space. Forexample, in response to detecting an occupancy condition in the space,the occupancy sensor 646 may transmit a digital message to the dimmerswitch 630 to cause the dimmer switch to turn on the lighting load 632,and in response to detecting a vacancy condition in the space, transmita digital message to the dimmer switch to cause the dimmer switch toturn off the lighting load. Alternatively, the occupancy sensor 646could be implemented as a vacancy sensor, such that the dimmer switch630 would only operate to turn off the lighting load 632 in response toreceiving the vacant commands from the vacancy sensor. Examples of RFload control systems having occupancy and vacancy sensors are describedin greater detail in commonly-assigned U.S. Pat. No. 7,940,167, issuedMay 10, 2011, entitled BATTERY-POWERED OCCUPANCY SENSOR; U.S. Pat. No.8,009,042, issued Aug. 30, 2011, entitled RADIO-FREQUENCY LIGHTINGCONTROL SYSTEM WITH OCCUPANCY SENSING; and U.S. patent application Ser.No. 12/371,027, filed Feb. 13, 2009, entitled METHOD AND APPARATUS FORCONFIGURING A WIRELESS SENSOR; the entire disclosures of which arehereby incorporated by reference.

The load control system 600 further comprises a battery-powered daylightsensor 648 for measuring an ambient light intensity in the space inwhich the daylight sensor in mounted. The daylight sensor 648 wirelesslytransmits digital messages via the RF signals 606 to the dimmer switch630. For example, the daylight sensor 648 may transmit a digital messageto the dimmer switch 630 to cause the dimmer switches to increase theintensities of the lighting load 632 if the ambient light intensitydetected by the daylight sensor 648 is less than a setpoint lightintensity, and to decrease the intensities of the lighting load if theambient light intensity is greater than the setpoint light intensity.The packet break time period T_(PKT) _(—) _(BRK) of the packetstransmitted by the daylight sensor 648 may be variable, for example, asa function of the measured light intensity. The battery-poweredmotorized window treatments 610 may be operable to receive digitalmessages from the occupancy sensor 646 and the daylight sensor 648 viathe RF signals 606 and to adjust the present position of the windowtreatments. Examples of RF load control systems having daylight sensorsare described in greater detail in commonly-assigned U.S. patentapplication Ser. No. 12/727,956, filed Mar. 19, 2010, entitled WIRELESSBATTERY-POWERED DAYLIGHT SENSOR, and U.S. patent application Ser. No.12/727,923, filed Mar. 19, 2010, entitled METHOD OF CALIBRATING ADAYLIGHT SENSOR, the entire disclosures of which are hereby incorporatedby reference.

The load control system 600 further comprises a battery-poweredtemperature control device 650 (e.g., a thermostat) that is operable tocontrol a heating and/or cooling system, e.g., a heating, ventilation,and air conditioning (HVAC) system 652. The temperature control device650 may be coupled to the HVAC system 652 via an HVAC communication link654, e.g., a digital communication link (such as an RS-485 link, anEthernet link, or a BACnet® link), or alternatively via a wirelesscommunication link (such as an RF communication link). The temperaturecontrol device 650 may comprise an internal temperature sensor fordetermining a present temperature in the space in which the temperaturecontrol device is located. The temperature control device 650 transmitsappropriate digital messages to the HVAC system 652 to control thepresent temperature in the building towards a setpoint temperature.Alternatively, the HVAC communication link 654 could comprise a moretraditional analog control link for simply turning the HVAC system 652on and off. The temperature control device 650 comprises a userinterface, e.g., a touch screen 656, for displaying the presenttemperature and the setpoint temperature, and for receiving user inputsfor adjusting the setpoint temperature. The temperature control device650 is operable to receive RF signals 606 from a wireless temperaturesensor 656 for determining the present temperature in the space, forexample, at a location away from the temperature control device 650. Inaddition, the motor drive units 620 of each of the motorized windowtreatments 610 may be operable to transmit the temperature measurementsfrom the internal and/or external temperature sensors 160, 162 to thetemperature control device 650.

Each of the battery-powered devices of the load control system 600(i.e., the tabletop button keypad 642, the remote control 644, theoccupancy sensor 646, the daylight sensor 648, and the temperaturecontrol device 650) is operable to enable their respective RFtransceivers at a sampling period T_(SAMPLE) (e.g., approximately 17.8msec) to detect if an RF signal 602 is presently being transmitted asdescribed above for the motorized window treatments 610. Each of thesebattery-powered devices is operable put its RF transceiver to sleep foran RF sleep time period T_(SLP-RF) that is much longer than the packettime period T_(PACKET) (e.g., approximately 5 msec) and to enable the RFtransceiver for the RF sample time period T_(SMPL-RF) that is muchshorter than the packet time period T_(PACKET) (e.g., approximately 17.3msec) so as to conserve battery power.

In addition, the load control system 600 could also comprise other typesof input devices and load control devices that each may put its RFtransceiver to sleep for an RF sleep time period T_(SLP-RF) that is muchlonger than the packet time period T_(PACKET). For example, theadditional types of input devices may comprise battery-powered remotecontrols, a temperature sensors, humidity sensors, security sensors,proximity sensors, keypads, key fobs, cell phones, smart phones,tablets, personal digital assistants, personal computers, timeclocks,audio-visual controls, safety devices, and central control transmitters.The additional types of load control devices may comprise, for example,an electronic dimming ballast for a fluorescent lamp; a driver for alight-emitting diode (LED) light source; a screw-in luminaire thatincludes a light source and an integral load regulation circuit; aswitching device for turning one or more appliances on and off; aplug-in load control device for controlling one or more plug-in loads; amotor control device for controlling a motor load, such as a ceiling fanor an exhaust fan.

The load control system 600 further comprises signal repeaters 660A,660B, which are operable to retransmit any received digital messages toensure that all of the control devices of the load control systemreceive all of the RF signals 606. The load control system 600 maycomprise, for example, one to five signal repeaters depending upon thephysical size of the system. Each of the control devices, (e.g., themotorized window treatments 610, the dimmer switch 630, the tabletopbutton keypad 642, the wall-mounted button keypad 640, the occupancysensor 646, the daylight sensor 648, and the temperature control device650) of the load control system 600 are located within the communicationrange of at least one of the signal repeaters 660A, 660B. The signalrepeaters 660A, 660B are powered by the AC power source 604 via powersupplies 662 plugged into electrical outlets 664.

According to the second embodiment of the present invention, one of thesignal repeaters (e.g., signal repeater 660A) operates as a “main”repeater (i.e., a main controller) to facilitate the operation of theload control system 600. The main repeater 660A has a database, whichdefines the operation of the load control system, stored in memory. Forexample, the main repeater 660A is operable to determine which of thelighting load 632 is energized and to use the database to control anyvisual indicators of the dimmer switch 630 and the keypads 642, 640accordingly to provide the appropriate feedback to the user of the loadcontrol system 600. In addition, the control devices of the load controlsystem may be operable to transmit status information to the signalrepeaters 660A, 660B. For example, the motor drive unit 620 of each ofthe motorized window treatments 610 may be operable to transmit adigital message representative of the magnitude of the respectivebattery voltage to the signal repeaters 660A, 660B, a digital messageincluding a low-battery indication to the signal repeaters whenoperating in the low-battery mode, or a digital message representativeof the present position P_(PRESET) of the motorized window treatment.

As mentioned above, the load control system 600 may comprise one to fivesignal repeaters depending upon the physical size of the system. Thecontrol devices of the load control system 600 are each operable toadjust the RF sampling period T_(SAMPLE) in response to the total numberN_(RPTR) of signal repeaters within the load control system 600.Specifically, each control device is operable to adjust the RF sleeptime period T_(SLP-RF), while keeping the RF sampling time periodT_(SMPL-RF) constant. The control devices adjust the respective samplingperiods because packets of data may be transmitted differently via theRF signals 606 depending on the number of repeaters in the load controlsystem 600. In particular, the packet break time period T_(PKT) _(—)_(BRK) of the data transmissions may vary in response to the number ofrepeaters to ensure that the signal repeaters in the load control system600 have sufficient time to propagate a given packet. Because the packetbreak time period T_(PKT) _(—) _(BRK) is a factor in appropriatelysizing the RF sleep time period T_(RF) _(—) _(SLEEP) of each of thecontrol devices to ensure that an RF sampling event coincides with apacket transmission as discussed above with respect to FIG. 8, the RFsleep time period T_(RF) _(—) _(SLEEP) also varies accordingly if thepacket break time period T_(PKT) _(—) _(BRK) of a transmitted packetvaries.

FIG. 15 is a simplified flowchart of an RF sampling rate selectionprocedure 800 that may be executed by any of control devices of the loadcontrol system 600, e.g., the motor drive unit 620. Typically, thissampling rate procedure 800 may be executed during a configuration ofthe motor drive unit 612. In the event that there is at least one signalrepeater (e.g., signal repeater 660A) in the load control system 600,that signal repeater will send a message to the motor drive unit 620 toinform the motor drive unit of the total number of repeaters N_(RPTR) inthe load control system. At step 810, the motor drive unit 620determines whether it has received a packet containing the number ofrepeaters N_(RPTR). In the event that the motor drive unit 620 has notreceived such a packet, then the motor drive unit assumes that it isoperating in a load control system that contains no signal repeaters. Asa result, the motor drive unit 620 uses a first RF sleep time periodvalue T_(SLP-RF1) (e.g., approximately 17.8 msec) as the RF sleep timeperiod T_(SLP-RF) at step 812 before the RF sampling rate selectionprocedure 1100 exits.

If the motor drive unit 620 has received a packet containing the numberof repeaters N_(RPTR), the motor drive unit determines whether thenumber of repeaters N_(RPTR) is greater than three at step 814. If thenumber of repeaters N_(RPTR) is not greater than three at step 814, themotor drive unit 620 uses the first RF sleep time period valueT_(SLP-RF1) (e.g., approximately 17.8 msec) as the RF sleep time periodT_(SLP-RF) at step 816 before the sampling rate selection procedure 800exits. If the number of repeaters N_(RPTR) is greater than three at step814, the motor drive unit 620 uses a second RF sleep time period valueT_(SLP-RF2) (e.g., approximately 16.3 msec) as the RF sleep time periodT_(SLP-RF) at step 818 before the RF sampling rate selection procedure800 exits. The RF sampling rate selection procedure 800 ensures that themotor drive unit 620 adjusts its RF sampling rate T_(SAMPLE) in responseto the number of repeaters in the load control system 600 to optimizereliability, response time, and battery life. The other battery-powereddevices of the load control system 600 (i.e., the tabletop button keypad642, the remote control 644, the occupancy sensor 646, the daylightsensor 648, and the temperature control device 650) may also execute theRF sampling rate selection procedure 800.

The RF transceivers of the control devices of the load control system600 are characterized by a signal strength threshold which is used todetect the transmitted RF signals 606. Particularly, the RF transceiverof each of the control devices of the load control system 600 ischaracterized by an adjustable signal strength threshold. FIG. 16 is asimplified graph illustrating various signal strength thresholds of, forexample, the RF transceiver of one of the motor drive units 620. Inparticular, FIG. 16 illustrates two signal strength thresholds of the RFtransceiver: a first threshold 860 (i.e., an extended battery threshold)and a second threshold 870 (i.e., an extended range threshold) having alower magnitude than the first threshold. The first and secondthresholds 860, 870 reside between a noise floor 880 and a signalstrength 850 of the nearest signal repeater (e.g., one of the signalrepeaters 660A, 660B). While FIG. 16 is described with reference to themotorized window treatments 620, the other battery-powered devices ofthe load control system 600 (i.e., the tabletop button keypad 642, theremote control 644, the occupancy sensor 646, the daylight sensor 648,and the temperature control device 650) may also have RF transceivershaving adjustable signal strength thresholds.

During a configuration or set-up procedure of each of the motor driveunits 620, a user may be operable to select the signal strength of theRF transceiver as having either the first threshold 860 or the secondthreshold 870. When using the second threshold 870 to detect RF signals606, the RF transceiver is operable to detect RF signals of a lowersignal strength which can improve the range performance of the RFtransceiver (i.e., the RF transceiver can detect RF signals sent fromcontrol devices that are located farther away). However, the secondthreshold 870 may cause the RF transceiver to be more sensitive to noiseevents as the noise floor 880 may occasionally exceed the secondthreshold. Each time the RF transceiver receives any RF energy (RFsignals 606, RF noise, etc.) that exceeds the second threshold 870during the RF sampling time period T_(SMPL-RF), the RF transceiver wakesup the controller of the motor drive unit 620, such that the controllerthen consumes additional power which ultimately reduces the life of thebatteries of the motor drive unit. When the RF transceiver uses thefirst threshold 860 to detect RF signals 606, the RF transceiver is lesslikely to detect RF signals having a lower signal strength, but is lesssusceptible to noise events. Because the RF transceiver only responds toRF energy (RF signals 606, RF noise, etc.) that exceeds the firstthreshold 860, the RF transceiver does not wake up the controller asfrequently as when the second threshold 870 is used. As a result, thelife of the batteries can be further extended when the RF transceiveruses the first threshold 660.

The first and second thresholds 860, 870 may be predetermined values.For example, the first threshold 860 may have a value of approximately−90 dBm and the second threshold 670 may have a value of approximately−97 dBm. Alternatively, the value of the adjustable threshold of the RFtransceiver could be determined automatically during the configurationprocedure of the motor drive unit 620. For example, the RF transceivermay be operable to detect an average magnitude of the noise floor 880and may also be able to detect a magnitude of the signal strength 850 ofthe nearest signal repeater 660A, 660B, and then provide thesemagnitudes to the controller of the motor drive unit. The controller maythen calculate an optimal value of a threshold for the RF transceiverthat will preserve battery life and provide appropriate rangeperformance. For example, the controller may halve the sum of themagnitude of the noise floor 880 and the magnitude of the signalstrength 850 of the nearest signal repeater to calculate the value ofthe threshold for the RF transceiver. In addition, in the event that thecalculated threshold value of the RF transceiver is too close (e.g.,within ˜5 dBm) to the noise floor 880, the load control system 600 maybe operable to prompt a user, e.g., through a programming interface (notshown), to add another signal repeater to the system. By adding anothersignal repeater to the system, the magnitude of the signal strength ofthe nearest signal repeater may increase, thus increasing the calculatedthreshold of the RF transceiver. As a result, the battery life of eachof the motor drive units 620 may be further extended.

During the configuration process of the load control system 600, themotor drive units 620 are each assigned to a particular frequencychannel such that each motor drive can receive RF signals 606transmitted on that frequency channel. During normal operation, themotor drive units 620 will each detect any packet of information that istransmitted on the respective assigned frequency channel—even if thatpacket does not contain data that is addressed to the motor drive unit.As soon as the RF transceiver of each motor drive unit 620 begins todetect a packet transmitted on the assigned frequency channel, the RFtransceiver will wake up the controller of the motor drive unit aspreviously described. The controller will then process the packet todetermine whether it must adjust the present position P_(PRES) of themotorized window treatment 610. In the event that the packet is notaddressed to the motor drive unit 620 (e.g., the packet containsinformation only for a dimmer switch 630), the controller will take nofurther action and will go back to sleep. However, because thecontroller woke up to process the packet, the controller consumed powerunnecessarily, and negatively impacted the life of the batteries of themotor drive unit 620.

Because the load control system 600 comprises many devices that areoperable to send and/or receive RF signals 606, there can be a verylarge number of packets regularly transmitted within the system. Many ofthese packets may not be addressed to the motor drive units 620, and asa result, need not be processed by the controller of each of the motordrive units. According to an aspect of the present invention, thebattery-power motorized window treatments 610 may be configured to onlylisten to RF signals 606 transmitted on an alternate channel distinctfrom the channels used by the other devices of the load control system600.

FIG. 17 is a simplified flowchart of an RF monitoring procedure 900performed by a main repeater (e.g., the signal repeater 660A) of theload control system 600. At step 910, the main repeater 660A configuresall of the control devices of the load control system 600 to use a givenfrequency channel (e.g., frequency channel A). At step 912, the mainrepeater 660A is operable to monitor a number N of RF packetstransmitted within a given time frame during normal operation. At step914, the main repeater 660A compares the number N of RF packets to apredetermined maximum number N_(MAX) to determine whether the loadcontrol system 600 has a high amount of traffic on frequency channel A.If the number N of RF packets is greater than the predetermined maximumnumber N_(MAX) at step 914, the main repeater 660A configures all of thebattery-powered motorized window treatments 610 to listen only to analternate frequency channel (e.g., frequency channel B). Otherwise, themain repeater 660A simply exits the RF monitoring procedure 900 withoutchanging the channel configuration of the battery-powered motorizedwindow treatments 610. Alternatively, the main repeater 660A couldsimply configure all battery-powered motorized window treatments 610 touse the alternate frequency channel (i.e., frequency channel B) in lieuof executing the RF monitoring procedure 900.

FIG. 18 is a simplified flowchart of an RF signal receiving procedure1000 performed by the signal repeaters (e.g., the signal repeater 660A)of the load control system 600 during normal operation when an alternatefrequency is in use. At step 1010, the signal repeater 660A receives apacket transmitted on frequency channel A. At step 1012, the signalrepeater 660A determines whether the received packet is addressed to atleast one of the battery-powered motorized window treatments 610. If thepacket is not addressed to any of the battery-powered motorized windowtreatments 610 (e.g., the packet is addressed to the dimmer switch 630),then the repeater 660A simply retransmits the packet on channel A atstep 1014 before the RF signal receiving procedure 1000 exits. However,if the signal repeater 660A determines that the received packet isaddressed to at least one of the battery-powered motorized windowtreatments 610, the signal repeater changes its frequency channel fromchannel A to channel B at step 1016 and transmits the received packet onfrequency channel B to the battery-powered motorized window treatments610 at step 1018. Finally, the signal repeater 660A changes itsfrequency channel from channel B back to channel A at step 1020 and theRF signal receiving procedure 1000 exits.

FIG. 19 is a simplified diagram of a RF load control system 1100 havingtwo signal repeaters 1160A, 1160B coupled together via a digitalcommunication link 1166 according to a third embodiment of the presentinvention. The first signal repeater 1160A is configured to transmit andreceive packets via the RF signals 606 using only the primary frequencychannel A, and the second signal repeater 1160B is configured totransmit and receive packets via the RF signals 606 using only thealternate frequency channel B. The first and second signal repeaters1160A, 1160B are operable to transmit digital messages to each other viathe digital communication link 1166, which may comprise, for example, awired communication link, such as an RS-485 link or an Ethernet link,link, or alternatively may comprise a wireless communication link, suchas an RF communication link.

In the event that the first signal repeater 1160A receives an packetthat is transmitted on channel A and is addressed to at least one of thebattery-powered motorized window treatments 610, the signal repeater1160A transmits a digital message (e.g., including the data from thepacket) to the second signal repeater 1160B via the digitalcommunication link 1166. Upon receiving the information via the digitalcommunication link 1160B, the second signal repeater 1160B transmits thepackets to the battery-powered motorized window treatments 610 via theRF signals 606 using the alternate frequency B. The packets transmittedto the motorized window treatments 610 by the second signal repeater1160B include the same (or similar) data as the packets that werereceived by the first signal repeater 1160A. Thus, the battery-poweredmotorized window treatments 610 only listen to RF signals 606transmitted on the alternate frequency channel B distinct from thechannel used by the other devices of the load control system 600 inorder to further preserve the battery life of the battery-powered windowtreatments.

Examples of battery-powered remote controls and RF control systems aredescribed in greater detail in commonly-assigned U.S. patent applicationSer. No. 12/399,126, filed Mar. 6, 2009, entitled WIRELESSBATTERY-POWERED REMOTE CONTROL HAVING MULTIPLE MOUNTING MEANS; U.S. Pat.No. 7,573,208, issued Aug. 22, 2009, entitled METHOD OF PROGRAMMING ALIGHTING PRESET FROM A RADIO-FREQUENCY REMOTE CONTROL, and U.S. patentapplication Ser. No. 12/033,223, filed Feb. 19, 2008, entitledCOMMUNICATION PROTOCOL FOR A RADIO-FREQUENCY LOAD CONTROL SYSTEM, theentire disclosures of which are hereby incorporated by reference.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

1. A load control device for controlling an electrical load receivingpower from a power source in response to RF signals transmitted by an RFtransmitter, the RF transmitter adapted to transmit a number ofsequential digital messages at a predetermined transmission rate, eachof the digital messages including the same command and characterized bya packet length, the load control device comprising: an RF receiveradapted to receive at least one of the sequential digital messages, theRF receiver enabled for a sample time period to determine if the RFtransmitter is transmitting one of the digital messages, the RF receiverentering a sleep mode for a sleep time period between consecutive sampletime periods; and a controller operatively coupled to the RF transceiverfor receiving the at least one of the sequential digital messages, thecontroller operable to control the load in response to the receiveddigital message; wherein the sleep time period of the RF receiver islonger than the packet length of each of the digital messages.
 2. Theload control device of claim 1, further comprising: a battery forpowering the controller and the RF receiver.
 3. The load control deviceof claim 2, wherein the controller can be controlled into a sleep modein which the controller consumes less power than in a normal mode. 4.The load control device of claim 3, wherein the RF receiver is operableto determine if detected RF energy exceeds a detect threshold, the RFreceiver operable to wake up the controller from the sleep mode to enterthe normal mode in response to determining that the detected RF energyexceeds the detect threshold.
 5. The load control device of claim 4,wherein the controller is operable to put the RF receiver and thecontroller to sleep for a snooze time in response to determining thatthe detected RF energy exceeds the detect threshold, the RF receiver andthe controller waking up after the snooze time, such that the controlleris operable to receive one of the digital messages.
 6. The load controldevice of claim 5, wherein the snooze time is slightly less than a breaktime between two subsequent ones of the sequential digital messages. 7.The load control device of claim 4, wherein the controller is operableto adjust the detect threshold of the RF receiver whereby the detectthreshold can be increased to prevent noise signals from causing the RFreceiver to wake up the controller thereby conserving battery power. 8.The load control device of claim 7, wherein the controller is operableto adjust the detect threshold from an extended range threshold close toa noise floor to an extended battery mode threshold greater than theextended range threshold.
 9. The load control device of claim 2, whereinthe electrical load comprises a motor for adjusting a covering materialof a motorized window treatment, the load control device comprising: amotor drive circuit coupled to the motor for driving the motor to thusopen and close the covering material.
 10. The load control device ofclaim 9, further comprising: a drive shaft; and at least one lift cordrotatably received around the drive shaft and extending to a bottom ofthe covering material for raising and lowering the covering material;wherein the motor is operatively coupled to the drive shaft such thatthe motor is operable to raise and lower the covering material byrotating the drive shaft.
 11. The load control device of claim 2,further comprising: at least visual indicator operable to display anindication of the state of the load.
 12. The load control device ofclaim 11, wherein the load control device comprises a battery-poweredremote control.
 13. The load control device of claim 2, wherein the loadcontrol device comprises a temperature control device operable tocontrol a heating and/or cooling system in response to the receiveddigital message.
 14. The load control device of claim 1, furthercomprising: a controllably conductive device adapted to be coupled inseries electrical connection between the source and the load forcontrolling the power delivered to the load; wherein the controller isoperatively coupled to a control input of the controllably conductivedevice for controlling the power delivered to the load in response tothe received digital message.
 15. The load control device of claim 14,further comprising: a power supply coupled in parallel electricalconnection with the controllably conductive device, the power supplyoperable to conduct a charging current through the load in order togenerate a DC supply voltage for powering the controller.
 16. The loadcontrol device of claim 14, further comprising: a ground terminaladapted to be coupled to earth ground; and a power supply adapted toconduct a charging current through the ground terminal in order togenerate a DC supply voltage for powering the controller.
 17. The loadcontrol device of claim 14, wherein the load comprises a lighting loadand the load control device comprises a dimmer switch for controllingthe amount of power delivered to the lighting load to adjust theintensity of the lighting load.
 18. The load control device of claim 1,wherein a packet break time period exists between any two consecutivepackets, the sample time period and the sleep time period of the RFreceiver sized such that at least one of the number of sequentialdigital messages coincides with one of the sample time period of the RFreceiver.
 19. An RF communication system comprising: an RF transmitteradapted to transmit a number of sequential digital messages at apredetermined transmission rate, each of the digital messages includingthe same command and characterized by a packet length; and an RFreceiver adapted to receive at least one of the sequential digitalmessages, the RF receiver enabled for a sampling time to determine ifthe RF transmitter is transmitting one of the digital messages, the RFreceiver entering a sleep mode for a sleep time period betweenconsecutive sample time periods; wherein the sleep time period of the RFreceiver is longer than the packet length of each of the digitalmessages.
 20. The RF communication system of claim 19, furthercomprising: a plurality of control devices operable to receive RFsignals transmitted on a first frequency.
 21. The RF communicationsystem of claim 20, further comprising: a signal repeater operable toreceive a first RF signal transmitted on the first frequency by one ofthe control devices, the signal repeater operable to determine that thefirst RF signal is intended for the RF receiver, the signal repeateroperable to change transmission frequencies and transmit a second RFsignal related to the first RF signal to the RF receiver on a secondfrequency different than the first frequency.
 22. The RF communicationsystem of claim 21, wherein the signal repeater is operable to determinethe number of the plurality of control devices, and to transmit thesecond RF signal to the RF receiver on the second frequency only if thenumber of control devices exceeds a threshold amount.
 23. The RFcommunication system of claim 20, further comprising: a first signalrepeater operable to receive a first RF signal transmitted on the firstfrequency by one of the control devices; and a second signal repeatercoupled to the first signal repeater via a communication link; whereinthe first signal repeater is operable to transmit a digital message tothe second signal repeater via the communication link in response toreceiving the first RF signal, the second signal repeater operable totransmit a second RF signal to the RF receiver on a second frequencydifferent than the first frequency in response to receiving the digitalmessage from the first signal repeater via the communication link. 24.The RF communication system of claim 23, wherein the communication linkcomprises a wired communication link.
 25. The RF communication system ofclaim 20, wherein the RF transmitter is operable to transmit thesequential digital messages to the RF receiver on a second frequencydifferent than the first frequency.
 26. The RF communication system ofclaim 19, wherein the RF receiver comprises a battery for powering theRF receiver.
 27. The RF communication system of claim 26, wherein the RFreceiver comprises a battery-powered motorized window treatment foradjusting the position of a covering material.
 28. The RF communicationsystem of claim 26, wherein the RF receiver comprises a battery-poweredremote control having a visual indicator.
 29. The RF communicationsystem of claim 26, wherein the RF receiver comprises a temperaturecontrol device operable to control a heating and/or cooling system. 30.The RF communication system of claim 19, wherein the RF receivercomprises a load control device adapted to be coupled in serieselectrical connection between an AC power source and an electrical loadfor controlling the power delivered to the load.
 31. The RFcommunication system of claim 30, wherein the load control devicecomprises a two-wire device adapted to be coupled in series electricalconnection between the AC power source and the electrical load without aconnection to the neutral side of the AC power source.
 32. The RFcommunication system of claim 30, wherein the load control devicecomprises a ground terminal adapted to be coupled to earth ground, theload control device operable to conduct a charging current for aninternal power supply through the ground terminal.
 33. The RFcommunication system of claim 19, wherein the RF transmitter comprisesone of a battery-powered remote control, an occupancy sensor, a vacancysensor, a daylight sensor, a temperature sensor, a humidity sensor, asecurity sensor, a proximity sensor, a keypad, a key fob, a cell phone,a smart phone, a tablet, a personal digital assistant, a personalcomputer, a timeclock, an audio-visual control, a safety device, and acentral control transmitter.
 34. The RF communication system of claim19, wherein a packet break time period exists between any twoconsecutive packets, the sample time period and the sleep time period ofthe RF receiver sized such that at least one of the number of sequentialdigital messages coincides with one of the sample time period of the RFreceiver.
 35. A wireless signal receiver comprising: a wireless receivercircuit for detecting transmitted signals transmitted in a predeterminednumber of packets, where each packet comprises the same data, therebeing a packet time and a time between packets substantially longer thanthe packet time; and a control circuit for turning on the wirelessreceiver circuit for an on-time, the on-time being substantially lessthan an off-time of the wireless receiver circuit, the on-time of thewireless receiver circuit being substantially less than the packet timeand the off-time between on-times being less than the time betweenpackets; wherein the off-time is selected so that within the pluralityof packets, the on-time will coincide with the packet time to ensurethat the wireless receiver circuit detects at least one packet duringthe transmission of the predetermined number of packets if packets arebeing transmitted.
 36. The wireless signal receiver of claim 35, whereinthe wireless signals are RF signals.
 37. The wireless signal receiver ofclaim 36, further comprising: an antenna coupled to the RF receivercircuit; and a filter circuit comprising a SAW filter coupled betweenthe antenna and the RF receiver circuit for filtering out frequenciesoutside of a defined frequency range; wherein said RF receiver circuitremains on if an RF signal is detected, and said filter circuit preventsaid RF receiver circuit from remaining on or turning on again for RFsignals outside of said frequency range, thereby conserving batterypower.
 38. The wireless signal receiver of claim 37, wherein the RFreceiver circuit is operable to turn on a control circuit in response todetecting the RF signal.
 39. The wireless signal receiver of claim 35,wherein the on-time is approximately 0.1 msec, the off-time isapproximately 40 msec, the packet time is approximately 5 msec and thetime between packets is approximately 75 msec.
 40. The wireless signalreceiver of claim 39, wherein the predetermined number of packetscomprises twelve.
 41. The wireless signal receiver of claim 35, furtherwherein the wireless signal receiver is battery powered and furthercomprising an adaptive circuit for changing the off-time of saidreceiver circuit to optimize battery life.
 42. A method of communicatingdigital messages in a load control system, the method comprising:transmitting a number of sequential digital messages at a predeterminedtransmission rate, each of the digital messages including the samecommand and characterized by a packet length; enabling an RF receiverfor a sample time period to determine if the RF transmitter istransmitting one of the digital messages; and putting the RF receiver ina sleep mode for a sleep time period between consecutive sample timeperiods; wherein the sleep time period of the RF receiver is longer thanthe packet length of each of the digital messages.
 43. The method ofclaim 42, further comprising: the RF receiver determining if detected RFenergy exceeds a detect threshold; and the RF receiver waking up acontroller from a sleep mode to enter a normal mode in response todetermining that the detected RF energy exceeds the detect threshold.44. The method of claim 43, further comprising: the controller puttingthe RF receiver and the controller to sleep for a snooze time inresponse to determining that the detected RF energy exceeds the detectthreshold; the RF receiver and the controller waking up after the snoozetime, the snooze time slightly less than a break time between twosubsequent ones of the sequential digital messages; and the controllersubsequently receiving at least one of the digital messages.
 45. Themethod of claim 44, further comprising: the controller controlling thepower delivered to an electrical load in response to the receiveddigital message.
 46. The method of claim 43, further comprising: thecontroller adjusting the detect threshold of the RF receiver whereby thedetect threshold can be increased to prevent noise signals from causingthe RF receiver to wake up the controller thereby conserving batterypower.
 47. The method of claim 42, wherein a packet break time periodexists between any two consecutive packets, the sample time period andthe sleep time period of the RF receiver sized such that at least one ofthe number of sequential digital messages coincides with one of thesample time period of the RF receiver.
 48. A wireless signal receivercircuit for detecting wireless control signals and having an on/offoperation to conserve power comprising: a control circuit; a wirelessreceiver having an on state when it consumes power and an off state whenit consumes less power than consumed in the on state, the on statehaving a duration substantially shorter than the off state, whereby thewireless receiver receives wireless control signals during the on stateto be processed by the control circuit, the wireless control signalsbeing sent in packets with a packet time such that there is a predefinedtime between packets; and wherein the wireless receiver is operable toperiodically be in the on state for a sample time substantially lessthan the packet time to detect a wireless control signal, whereby upondetecting a first packet during the sample time, the wireless receiveris operable to enter the off state to conserve power for an amount oftime slightly less than the predefined time between packets, tosubsequently turn on and remain on until a succeeding packet starts tobe received, and to turn off after the succeeding packet is fullyreceived.
 49. The wireless signal receiver circuit of claim 48, whereinthe control circuit has an on state when it consumes power and an offstate when it consumes less power than consumed in the on state, thewireless receiver operable to cause the control circuit to enter the onstate in response to detecting the wireless control signals.
 50. Thewireless signal receiver circuit of claim 49, wherein upon the wirelessreceiver detecting the first packet, the control circuit is operable todetermine that the wireless receiver did not receive the first packet inits entirety.
 51. The wireless signal receiver circuit of claim 50,wherein upon the control circuit determining that the wireless receiverdid not receive the first packet in its entirety, the control circuit isoperable to cause the wireless receiver to enter the off state and toenter the off state itself to conserve power for an amount of timeslightly less than the predefined time between packets.
 52. The wirelesssignal receiver circuit of claim 48, wherein the wireless controlsignals are RF signals.
 53. The wireless signal receiver circuit ofclaim 48, wherein the control circuit comprises a microprocessor. 54.The wireless signal receiver circuit of claim 48, wherein if thewireless receiver does not detect a wireless signal during the on state,the wireless receiver turns off until a next on state.
 55. Abattery-powered wireless device comprising: a control circuit having anon state when it consumes power and an off state when it consumes lesspower than consumed in the on state; and a wireless receiver circuitoperable to periodically check for wireless signals, the wirelessreceiver circuit having a detect threshold wherein the wireless receivercircuit is operable to determine whether a wireless signal exceeds thedetect threshold, the receiver circuit operable to cause the controlcircuit to be in on state in response to determining that a wirelesssignal exceeds the detect threshold; wherein the control circuit isfurther operable to adjust the detect threshold of the wireless receivercircuit whereby the detect threshold can be increased to prevent noisesignals from causing the wireless receiver circuit to turn on thecontrol circuit thereby conserving battery power.
 56. The batterypowered wireless receiver of claim 55, wherein there are at least twodetect thresholds comprising an extended range threshold close to anoise floor and an extended battery mode threshold above the extendedrange threshold.
 57. A system for conserving battery power of a batterypowered wireless signal receiver comprising: a wireless signal receiverthat periodically turns on to determine if a wireless signal is beingtransmitted, the wireless signal receiver being capable of receiving onany of multiple channels, the wireless signal receiver including acontrol circuit that determines if the wireless signal is intended forthe wireless signal receiver; and a transceiver circuit forretransmitting said wireless signals, the transceiver circuitdetermining a number of transmitted wireless signals, and if the numberexceeds a threshold amount, said transceiver circuit communicating withthe wireless signal receiver to change the channel of communication toan alternate channel and retransmitting wireless signals intended forthe wireless signal receiver on the alternate channel, whereby thewireless signal receiver will receive fewer wireless signals on thealternate channel, thereby remaining on for less time and reducingbattery power consumption.
 58. The system of claim 57, wherein thetransceiver comprises a repeater for retransmitting the wireless signalsfrom a plurality of transmitting devices.
 59. The system of claim 58,wherein the repeater automatically switches to a less used alternatechannel when the threshold amount is exceeded.
 60. The system of claim58, wherein the plurality of transmitting devices include at least onetransmitter for controlling a battery powered motorized windowtreatment.
 61. The system of claim 58, wherein the multiple channelshave different carrier frequencies.
 62. The system of claim 57, whereinthe wireless signals are RF signals.
 63. A wireless control systemcomprising: a first wireless signal receiver capable of receiving onwireless signals on a first channel; a second wireless signal receiverthat periodically turns on to determine if wireless signals are beingtransmitted, the second wireless signal receiver being capable ofreceiving on wireless signals on a second channel; and a transceivercircuit for retransmitting said wireless signals, said transceivercircuit operable to receive a first wireless signal on the first channeland to determine that the first wireless signal contains controlinformation intended for the second wireless signal receiver, thetransceiver circuit operable to change its channel of communication fromthe first channel to the second channel, the transceiver circuittransmitting the control information in a second wireless signal to thesecond wireless signal receiver on the second channel.
 64. The wirelesscontrol system of claim 63, wherein the transceiver circuit is operableto change its channel of communication from the second channel to thefirst channel, after transmitting the control information in the secondwireless signal to the second wireless signal receiver on the secondchannel.